As shown in FIG. 1, the structure of a conventional GaN-based light-emitting diode includes a substrate 1, a buffer layer 2 grown on substrate 1, an n-type GaN layer 3 grown on buffer layer 2, a light-emitting layer 4 grown on n-type GaN layer 3, and a p-type GaN layer 5 grown on light-emitting layer 4. The light-emitting diode is manufactured with the following steps:
(1) Using the inductively coupled plasma-reactive ion etching (ICP-RIE) dry etching method to etch downward through p-type GaN layer 5, light-emitting layer 4, and reach n-type GaN layer 3 in order to form an n-metal forming area 6 of about 1 um deep, as shown in FIG. 2A;
(2) Forming a transparent and conductive first ohmic contact electrode 7 on p-type GaN layer 5, as shown in FIG. 2B;
(3) Forming a second ohmic contact electrode 8 on n-metal forming area 6, as shown in FIG. 2C; and
(4) Forming pads 9 on both first ohmic contact electrode 7 and second ohmic contact electrode 8, as shown in FIG. 2D.
Thus, a conventional GaN-based light-emitting diode is manufactured.
In the aforementioned conventional method, a transparent conductive layer 7 is made of Ni/Au, which has a low optical transmittancy. Therefore, the external quantum efficiency of the manufactured light-emitting diodes is poor.